Vinyl flooring failures are usually a result of a failure within the installation system below the floor covering.  

A complete system typically includes surface preparation, a levelling screed, a moisture barrier and/or primer and a vinyl adhesive. This can change depending on the system and installation requirements. 

This article identifies the biggest issues that arise relating to the adhesives used to install vinyl flooring, with practical advice from the industry on how to avoid failures. 

Talking trowels  

Glue down vinyl sheeting and luxury vinyl tiles (LVTs) adhesives should be applied with the right sized trowel to ensure a sufficient amount of adhesive on the floor. In general, these trowels have smaller, triangular (serrated) notches of 1,5 x 1,5mm with 4mm centres, a TKB standard A2 blade. versus tile adhesive trowels, which have larger, square notches of 3mm to 10mm.  

An incorrect trowel, such as a cementitious tile adhesive trowel, will leave too much adhesive on the substrate, which will take too long to dry, and the excess glue will bleed through the joints, making a gap and pushing the LVTs apart. Acrylic Adhesive in its thick form is elastic and spongy, and does not serve its purpose anymore. Excess adhesive use also pushes up costs on the project unnecessarily. 

The right trowel ensures an even spread of adhesive, for good coverage and contact under the vinyl flooring. This further allows for a more accurate estimation of the volume of vinyl adhesive required to complete the installation. Too little adhesive underneath the vinyl will ultimately cause the flooring to lift. 

In some cases, the vinyl adhesive can be applied with a new short-pile mohair paint roller, a short-haired velour or a foam roller. Always follow the manufacturer’s recommendations, as per the technical data sheet (TDS). 

Top tip: Trowels have a lifespan, as the serrations can wear down from frequent use. Over time it should be replaced, to ensure the right volume of adhesive and an even spread. 

Moisture management 

It is not necessarily only the vinyl flooring itself that is affected by excess moisture in the substrate. The vinyl adhesives are very sensitive to moisture, and when the moisture levels are too high, without the intervention of a suitable moisture barrier, the adhesive may re-emulsify and is no longer effective. This causes the vinyl flooring to “bubble” or delaminate from the substrate. 

Make sure the moisture readings for the substrate comply with the requirements of the floor coverings’ manufacturer. These are typically below 3% or below 75% relative humidity (RH). Where the moisture levels are above this level, a moisture barrier will be required, particularly if it is an acrylic or water-based product. When choosing a moisture barrier, confirm that the product is suited for the tested moisture levels as per the product’s TDS. 

Top tip: The use of a vapour barrier, particularly on surface beds, even where the substrate seems dry, safeguards the installation. 

Site control 

Site control both before and during installation, and for the full curing time, is very important. Vinyl flooring products and adhesives are thermo-responsive and should be placed in the application area for 24-48 hours prior to installation to acclimatise to the temperature in the space. This prevents expansion or contraction of the product, effectively moving in the wet adhesive, during installation. 

Temperature variations can also affect the adhesive bond, resulting in failures of the flooring installation. Areas with large windows or where the sun shines in may cause flash setting of the adhesive. These need to be closed or boarded up to ensure that a stable ambient temperature is maintained. 

Top tip: The temperature should not fluctuate beyond 10-15°C from the initial temperature during installation. 

Substrates 

Vinyl sheeting and LVTs require a smooth and level surface for best results. This is usually achieved by the installation of a self-levelling compound, or screed, onto which the final floor covering is applied.  

The majority of adhesives in South Africa are wet set, and can only be installed on an absorbent subfloor. Pressure sensitive adhesives can be used on both absorbent and non-absorbent surfaces. 

Adhesive flash-off time 

Not to be confused with open time, many vinyl adhesives need to “flash-off” before bedding the vinyl sheeting, or LVTs. Flash-off is when the adhesive is left to air or dry for a short time. This allows for all the solvents to escape, so that they don’t form bubbles below the vinyl sheeting. It should still feel slightly sticky or tacky to the touch. Bear in mind that the weather, temperature and humidity affect the amount of time required for product flash-off.  

In contrast, a pressure sensitive adhesive is applied, then left to dry completely. The product’s extended open time allows for installation onto the dry adhesive bed.  

There are also products on the market, more specifically for LVT flooring, that are designed for “wet” lay installations, which don’t require a flash-off time. The final glue line once set/cured is rigid, inhibiting lateral shear movement on the tiles once in service, thus reducing the possibility of “gapping” between the tiles over time. 

Top tip: During flash-off, protect the adhesive from dust and debris contamination. 

Too wet/too dry 

Installing vinyl over an adhesive that is too wet, may cause the adhesive to take a very long time to dry or not dry at all. The vinyl flooring can then warp, lift or have gaps between the tiles, or sheets. 

Be careful not to leave the adhesive too long, i.e., if there is no glue transfer when doing a touch test. Adhesive that has dried too long will not hold the vinyl flooring installation in place, not even with the use of the 68kg roller. The remedy is to scrape the dried adhesive off and start again, wasting time and money. 

Top tip: Once the product has flashed-off, the window of time to bed and roll the vinyl flooring is quite narrow, so careful timekeeping is key. 

68kg roller 

A 68kg roller should be rolled across the installed vinyl floor while the adhesive is still tacky and receptive, i.e. not the next day. The purpose of the roller is to flatten the adhesive ridge lines and bed the vinyl flooring firmly into the adhesive, eliminating any air bubbles that could cause a failure downstream. The use of a rubber mallet is not recommended. 

LVT flooring that is installed in a “wet” lay adhesive does not typically require rolling after installation. 

Top tip: Rolling should be done in cross-directionally. First in one direction, and then perpendicular to that for the best results, i.e., north/south and then an east/west direction.  

Curing times 

Allow the adhesive to fully cure, as per the adhesive manufacturer’s instructions, before subjecting the flooring to traffic or full-service conditions. Some products require a longer curing time before exposure of the floor to water or cleaning procedures. 

Top tip: Curing times of the adhesive may be affected by site and ambient conditions. 

Cleaning and care 

Some cleaning products can attack the adhesive due to a chemical reaction between them, which, over time, will damage the flooring installation. A pH-neutral cleaning product is best suited to keep vinyl sheeting and LVT flooring in a good condition. 

Top tip: Cleaners with harsh chemicals, such as dishwashing liquid, are strongly discouraged as they will cause degradation of the adhesive over time. 

Issue: How to avoid failures with vinyl adhesives. 

Solution: These top tips from the industry give practical advice on moisture, flash-off times and more. 

Thanks to iTe Products, TAL, Wakol for the information in this article.